Technical Field
The present disclosure relates to a motor controller and a method of controlling a stepping motor, and more particularly to a motor controller for use in an actuator and a method of controlling a stepping motor.
Background
The stepping motor has various features such as ease of control of the stepping motor and is widely used as multiple types of actuator (for example, see Japanese Patent Application Laid-Open No. H07-170790).
Examples of the actuator including a motor such as a stepping motor include an actuator for vehicular use in a low temperature environment such as in a place where the temperature is low. When the actuator is in such a low temperature environment, the lubricating oil applied to a drive unit of the actuator is accordingly hardened. When the actuator fallen into such a state is to be started, even if an effort is being made to operate the motor driving the actuator with a torque during steady operation (referred to as a state where the motor is in normal operation after the actuator started in a low temperature environment), the actuator cannot start, and a step-out may be detected.
In view of such a problem, Japanese Patent Application Laid-Open No. 2014-143775 discloses a motor controller capable of driving the motor even in a low temperature environment by performing boost control of drive power so that a drive power larger than that during steady drive is supplied to the motor only during the boost period after the motor started.
The drive method disclosed in Japanese Patent Application Laid-Open No. 2014-143775 requires a drive power larger than that during steady drive to be supplied to the motor during boost period. However, in some cases, the motor may be required to be driven by a predetermined drive power smaller than such a large drive power.